OsmoBTS¶

OsmoBTS is a software implementation of a GSM BTS.

It implements the follwing protocols/interfaces:

• LAPDm (GSM 04.06)
• RTP
• A-bis/IP in IPA multiplex
• OML (GSM TS 12.21)
• RSL (GSM TS 08.58)

OsmoBTS is building up on work done previosuly for OpenBSC (e.g. RSL, OML, RTP) and OsmocomBB (e.g. LAPDm). The Abis/IP protocol staking is inspired by ip.access A-bis/IP, sometimes called IPA multiplex.

OsmoBTS in the Osmocom architecture¶

Backends / Hardware support¶

OsmoBTS is modular and has support for multiple back-ends. A back-end talks to a specific L1/PHY implementation of the respective BTS hardware. Based on this architecture, it should be relatively easy to add a new back-end to support so-far unsupported GSM PHY/L1 and associated hardware.

So far OsmoBTS has been integrated with several different L1/PHY and hardware systems. The backends are:

• osmo-bts-sysmo
  • Multiple indoor and outdoor BTS products called sysmoBTS by sysmocom
• osmo-bts-trx
  • Wideband SDR transceiver hardware supported by OpenBTS transceiver or [OsmoTRX] PHY layer software, including the UmTRX, the USRP family, etc.
  • Multiple indoor and outdoor fairwaves BTSs, like UmDESK and UmSITE
• osmo-bts-litecell15
• osmo-bts-octphy
• osmo-bts-bb
  • A pretty crazy experimental BTS hardware based on two OsmocomBB phones had originally been supported, but needs to be re-integrated with core code changes.

Manuals¶

• User Manual: http://ftp.osmocom.org/docs/latest/osmobts-usermanual.pdf
• VTY Reference: http://ftp.osmocom.org/docs/latest/osmobsc-vty-reference.pdf
• Abis Protocol Manual: http://ftp.osmocom.org/docs/latest/osmobts-abis.pdf

Status¶

The source code includes a http://cgit.osmocom.org/cgit/osmo-bts/tree/README file with current status information

GPRS support¶

In the GSM architecture, the BTS is an element in the circuit-switched domain only.

For packet-switched support, OsmoBTS provides a socket interface towards OsmoPCU. This adds GPRS and EDGE support to it.

Source code¶

The source code is available from git.osmocom.org (module osmo-bts).

Public read-only access is available via
git clone git://git.osmocom.org/osmo-bts.git
You can browse it via cgit: http://cgit.osmocom.org/cgit/osmo-bts/

Authors / Credits¶

OsmoBTS was originally developed in 2011 by Andreas Eversberg and Harald Welte.

Today it is mostly maintained by Harald Welte and Holger Freyther at sysmocom. Exception is the osmo-bts-trx back-end which is maintained by Fairwaves.